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Science Talk: Eating Fried Eggs can Lower your Heart Risk

Has anyone ever told you bacon and eggs are bad for your heart? Well, take out the bacon, and you can tell them they are misinformed.

Despite the fact eggs contain all the basic nutrients for life, they have a bad reputation in the heart healthy world. Unfortunately, eggs are known for the undesirable 200-300mg of cholesterol found in egg yolks. Current guidelines for healthy Americans recommend eating 300mg or less cholesterol per day, and less than 200mg a day for individuals with increased heart risk. Those individuals used to eating a “hearty breakfast,” were suddenly thrown for a loop. After just one egg, recommended cholesterol allowance for the day has been spent! Well, egg lovers, take heart. A recent study from the Journal of Agricultural and Food Chemistry demonstrated a decrease in blood pressure from digestion of egg proteins, particularly in fried eggs. Yes! Eggs are healthy again!

High blood pressure is a very common condition in today’s society. Recent national studies show 31% of all U.S. adults are at risk for high blood pressure, or prehypertensive (>120/80mmHg, normal blood pressure is considered to be less than 120/80). High blood pressure is thought to be caused by one of three things: sodium/salt sensitivity, blood vessel constriction causing a rise in pressure, or increased stress causing an excitatory response in the body. High blood pressure puts undue stress on the vessels and can lead to heart attack, stroke,or heart failure. Most individuals diagnosed with high blood pressure (>140/90mmHg) are on medicine to prevent further medical complications.

ACE inhibitors are the most popular type of blood pressure medication. ACE stands for Angiotensin I Converting enzyme. ACE is the key enzyme which is responsible for regulation of blood pressure through the “rennin – angiotensin system.” ACE is responsible for constriction of the blood vessels causing an overall rise in pressure when needed. Person’s with high blood pressure may have an overactive ACE response, so ACE inhibitors are needed. This is the exact inhibitory enzyme found in protein from fried eggs that helps lower blood pressure. Hence, eggs are suddenly the good for you again.

Professor Gruen, from the Food Chemistry department in the University of Missouri, explains the egg phenomenon like this, “Eggs aren’t likely to contribute to heart disease because of the nature of ACE inhibitors, from the active proteins in eggs, that act like [blood pressure] drugs in our body.”

All proteins are made of smaller molecular structures called amino acids. There can be anywhere from 2,000 to 100,000 amino acids in a chain to make one protein. The active proteins in the study are in the form of a dipeptide, a chain of two amino acids. In order to break the large proteins in the egg, heat must be added to break the bonds between amino acids. The study from the Journal of Agriculture and Food Chemistry compared different cooking methods to the production of the ACE inhibiting proteins. They used very sophisticated measures to single out tiny protein strand and analyze which protein fractions are the most active inhibitors. Eggs were boiled and fried. They found the boiled eggs had less of the active ingredient for two main reasons. One, the eggs were boiled in water that could only reach 100°C while the fried eggs are not limited by a boiling point and could reach much higher temperatures. The higher the heat source, the easier it was to break apart the protein. The second reason is in the shape of the two cooked eggs. The boiled egg is heated gradually from the outside in; meanwhile, the fried egg has a much greater surface area that is heated more evenly. The heat from cooking helps to breakdown proteins throughout the entire egg. Dr Gruen explains it like this, “Proteins resemble a tight ball of yarn. When you heat a protein it loosens up the ball of yarn. Then, enzymes, a chemical meant to cut the protein, can cut into the yarn ball more effectively. These small clippings of yarn are active proteins that are easily digested and used by the body.”

Even though the study concluded that in vitro (test tube) egg digestion indicates a high absorption of active proteins to lower blood pressures, an in vivo (using human subjects) study is needed to confirm this assumption. Dr. Gruen says this is quite common to start with in vitro studies in order to apply for large grant money needed for human studies. When questioned, Dr. Jianping Wu, co-author for the study, confirmed plans for a second study using human subjects. Dr. Gruen believes the next logical step would be to use human subjects to study how many fried eggs would have to be consumed to be equivalent to one ACE inhibitor drug. As new information comes out, cardiac diet guidelines may be changing to include more eggs in the recommendations for heart health.

Bottom line, Dr. Gruen speculates that the bacon and egg breakfast American’s are trying to avoid “is probably not that bad for you,” and Jianping Wu assures me he eats eggs every morning.

I had to comment to tell you that the chicken scientist you met in Rio last year – has known Jianping for years – we’re in the same city. Small world, eh? ACE inhibitors in eggs are just the most amazing thing – the other ‘stuff’ they’re finding in eggs is very exciting.